Mutations in AtPS1 (Arabidopsis thaliana Parallel Spindle 1) Lead to the Production of Diploid Pollen Grains

Abstract

Polyploidy has had a considerable impact on the evolution of many eukaryotes, especially angiosperms. Indeed, most—if not all—angiosperms have experienced at least one round of polyploidy during the course of their evolution, and many important crop plants are current polyploids. The occurrence of 2n gametes (diplogametes) in diploid populations is widely recognised as the major source of polyploid formation. However, limited information is available on the genetic control of diplogamete production. Here, we describe the isolation and characterisation of the first gene, AtPS1 (Arabidopsis thaliana Parallel Spindle 1), implicated in the formation of a high frequency of diplogametes in plants. Atps1 mutants produce diploid male spores, diploid pollen grains, and spontaneous triploid plants in the next generation. Female meiosis is not affected in the mutant. We demonstrated that abnormal spindle orientation at male meiosis II leads to diplogamete formation. Most of the parent's heterozygosity is therefore conserved in the Atps1 diploid gametes, which is a key issue for plant breeding. The AtPS1 protein is conserved throughout the plant kingdom and carries domains suggestive of a regulatory function. The isolation of a gene involved in diplogamete production opens the way for new strategies in plant breeding programmes and progress in evolutionary studies.

Use of 2n Gametes in Plant Breeding

“…Barcaccia et al, 2000Barcaccia et al, , 2003Zhang et al, 2007). However, research on the model plant thale cress (Arabidopsis thaliana) has led to many recent advances in elucidating the molecular mechanisms as well as the first genes in which mutations result in the production of viable 2n gametes (for a review see Brownfield & Köhler, 2011). d'Erfurth et al (2008 were the first to successfully isolate and characterize a gene involved in 2n gamete production.…”

Production of Diploid Male Gametes in Arabidopsis by Cold-Induced Destabilization of Postmeiotic Radial Microtubule Arrays

“…Mutations in Arabidopsis DYAD/SWITCH1 and maize ARGO-NAUTE104 (AGO104) and AM1 induce a complete loss of MI and, consequently, convert the meiotic cell cycle into a mitotic one (Ravi et al, 2008;Pawlowski et al, 2009;Singh et al, 2011). Lesions in Arabidopsis OSD1/ GIG1 and TAM/CYCA2;1, two proteins involved in progression of the meiotic cell cycle, cause a complete loss of MII, generating highly homozygous 2n gametes in both male and female meiosis (d'Erfurth et al, 2009(d'Erfurth et al, , 2010. Spindle-based meiotic restitution mechanisms have been reported in both Arabidopsis jason and atps1 mutants and in the potato ps mutant, in which parallel, fused, and tripolar spindles in male MII lead to the formation of FDR 2n spores (Mok and Peloquin, 1975;d'Erfurth et al, 2008;De Storme and Geelen, 2011).…”

Occurrence of Univalents and Abnormal Spindle Activity in the Meiocytes in <i>Impatiens devendrae</i> Pusalkar from Western Himalayas

“…All these events resulted in reduction in pollen fertility. Such an abnormal spindle activity coupled with aberrant synapsis known to affect the meiotic course has also been observed in a number of flowering plants (Tilquin et al 1984, Qu and Vorsa 1999, Caetano-Pereira and Pagliarini 2001, Mendes-Bonato et al 2002, Risso-Pascotto et al 2005, d Erfurth et al 2008, Gulfishan et al 2010, Himshikha et al 2010. Gupta and Yashvir (1973), who have studied the meiotic irregularities in Setaria verticillata, found that the presence of univalents in the species leads to the formation of laggards and chromatin bridges and ultimately affect the meioisis.…”